A wide variety of absorbent structures designed not only to be efficient for the absorption of body fluids such as blood, urine, menses, and the like, but also to be sanitary and comfortable in-use are known in the literature. Disposable products of this type generally comprise some sort of fluid-permeable topsheet material, an absorbent core, and a fluid-impermeable backsheet material. Various shapes, sizes and thicknesses of such articles have been explored in an attempt to make their use more comfortable and convenient.
One particular aspect of sanitary products which has been under investigation for many years is that of odor control. Many body fluids have an unpleasant odor, or develop such odors when in contact with air and/or bacteria for prolonged periods. The literature is replete with references relating to odor control in products such as diapers and catamenials.
Various odor-controlling agents have been disclosed in the literature. In particular, certain zeolitic materials are becoming known for their odor-controlling properties. Zeolitic materials are generally quite safe, and while they do effectively control many odors associated with body fluids, it has been determined that, unfortunately, they do not provide optimal control for ammonia odor and similar odors, presumably associated with short-chain amines and/or urea.
Moreover, the zeolitic odor-controlling materials tend to be in the form of very small, dusty particles which are difficult to handle on a commercial scale. Such materials tend to be blown or vacuumed up from absorbent structures moving at the high speeds (500-600 items/minute) used on modern catamenial or diaper manufacturing lines.
It has been suggested that particulate odor-controlling agents can be adhered to the surface of larger particles of absorbent gelling materials using moisture. The resulting particles are less dusty, easier to handle and exhibit improved control of odors, including ammonia. However, it has now been discovered that such particles can typically be "loaded" with only up to about 10% by weight of odor-controlling agent using water. Preferably, the mixed absorbent gelling material/odor-controlling agent particle would contain greater than such a modest loading, more conveniently, on the order of a 20% or greater loading of said particulate odor-controlling agent.
Finally, it has now been determined that certain particulate odor-controlling agents can lose a portion of their odor-controlling activity during the manufacture of catamenials, diapers and the like. While the reason for this loss is not entirely clear, it is conceivable that the agents adsorb vagrant materials from the manufacturing process and, thus, their odor-adsorbing capacity is partially "used up".
Accordingly, it would be desirable to provide odor-controlling agents which would control not only complex odors, such as those the zeolitic materials handle easily, but also simple odors, such as ammonia. It would also be desirable to provide such agents in a form which is easy to handle.
The present invention provides a means for safely and effectively overcoming these deficiencies by combining particulate odor-controlling agents with absorbent gelling materials, using binder materials, as disclosed more fully hereinafter. These and other advantages associated with the present invention will be seen from the disclosure, hereinafter.